Social bookmarking is one of the most interesting trends in the current web environment. In a social bookmarking system, users annotate a web page with tags, which describe the contents of the page. Numerous studies have been done using this information, mostly on enhancing the quality of web search. In this paper, we use this information to measure the semantic similarity between two web pages. Since web pages consist of various types of multimedia data, it is quite difficult to compare the semantics of two web pages by comparing the actual data contained in the pages. With the help of social bookmarks, this comparison can be performed very effectively. In this paper, we propose a new similarity measure between web pages, called Web Page Similarity Based on Entire Tags (WSET), based on social bookmarks. The experimental results show that the proposed measure yields more satisfactory results than the previous ones.